COS 426 Assignment 2

COS 426, Spring 2011
Nader Al-Naji, nbal

I believe that I have implemented the following features, which are worth a total of 22 points:

Cube	Cheetah
Normals calculated by traversing half-edges for each vertex. To view these uncomment the call to UpdateNormal() in the UpdateVertexNormals() function.

Firefly-Human	Moo
Curvatures calculated by traversing half-edges for each vertex. First the area associated with each vertex was calculated, then the angle of deflection. The resulting value was then simply the area over the angle of deflection. Black vertices indicate concavity (c > 0) and blue vertices indicate convexity (c < 0). To view these, uncomment the call to UpdateCurvature() in the UpdateVertexCurvatures() function.

meshpro input/meshname.off output/meshname_randomnoise_factor.off -noise factor

Input	0.4	0.8
Each vertex moved by a random amount determined by the average length of its adjacent edges.

meshpro input/meshname_in.off output/meshname_out.off -inflate factor

Input	0.5	1	3
Each vertex moved outward along its normal by a factor determined by its average length and a user-specified value.

meshpro input/meshname_in.off output/meshname_out.off -fun

Input	Swirled
Each vertex is rotated in space by an angle determined by how far away it is from a central axis.

meshpro input/meshname_in.off output/meshname_out.off -smooth

Input	-smooth -smooth	-smooth -smooth -smooth -smooth
Each vertex is moved to a position determined by a linear combination of itself and its adjacent vertices.

meshpro input/meshname_in.off output/meshname_out.off -sharpen factor

Input	-sharpen -sharpen	-sharpen -sharpen -sharpen -sharpen
This is similar to smoothing except that the metric used to move vertices is reversed.

meshpro input/meshname_in.off output/meshname_out.off -truncate factor

Cube	Truncate .5	Surface of Revolution (made with -revolution)	Truncate .3
For each vertex, create a set of new vertices a distance t (given by user) along its outgoing edges. Remove the original vertex and add a face connecting the new vertices created together. Here this is shown on a cube and a surface of revolution.

meshpro input/meshname_in.off output/meshname_out.off -split

Input (inside a cube)	-split	-split -split	-split -split -split
Create V+1 faces for each face in the original mesh by splitting the edges of each face and connecting the newly created vertices together. Shown here is the result of applying this process multiple times on a cube. The face is being shown from the inside to avoid overlapping lines from the camera's perspective.

meshpro input/meshname_in.off output/meshname_out.off -loop

Input	-loop	-loop -loop	-loop -loop -loop
Split the faces of the mesh and then move vertices by an amount determined by predefined weights.

meshpro input/meshname_in.off output/meshname_out.off -revolution

Semi-Circle	Wine-Glass Profile	Wine-Glass Profile (after -truncate .5)
Create a surface by rotating a profile curve along an axis using a given angle step size. Here the wine-glass is then truncated to show that the rotation preserves the integrity of the half-edge data structure used. Note: this output was much easier to generate by hardcoding the arguments-- that is by putting a call to the method in the code and running it. If you'd like to produce the same output as seen here, rather than runing it using the command, simply uncomment the portion of ReadOff marked UNCOMMENT FOR SURFACE OF REVOLUTION and give it a profile as a mesh.

meshpro input/meshname_in.off output/meshname_out.off -sweep factor

Semi-Circle Along Perpendicular Semi-Circle	Semi-Circle Along Parallel Semi-Circle
Sweep a profile curve along another profile curve to produce a mesh. Note: this output, as above, was easier to generate by circumventing the command-line and hard-coding in the arguments. If you'd like to produce the same image, simply uncomment the UNCOMMENT FOR SURFACESWEEP portion of ReadOff and give it two profile curves.

This swirl reminds me of an episode of the twilight-zone so I'm making
it my art contest submission.

How long did you spend on this assignment?: I could have spent longer.
Was it too hard, too easy, or just right?: It was perfect.
What was the best part of the assignment?: I really liked Truncate and Loop Subdivision.
What was the worst part of the assignment?: Bug-hunting.
How could it be improved for next year?: Whatever you do, don't give them the half-edge data
structure. Figuring that out was arguably the most
enriching part of the assignment.